栅控电子通道中的非均匀流体动力学等离子体波不稳定性
Nonuniform Hydrodynamic Plasma-Wave Instability in a Gated Electron Channel
- Rensselaer Polytechnic Institute（伦斯勒理工学院）
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AI总结：
本文通过流体动力学模型研究电流驱动的栅控电子通道中非均匀等离子体波不稳定性，发现频率由全通道传播决定，不稳定性源于边界增益与损耗竞争，且有限粘性理论在亚声速区与模拟吻合。
AI中文摘要：
我们报告了对电流驱动的InGaAs/GaAs栅控电子通道中等离子体波不稳定性的理论和数值研究。有限的漏极电流使通道偏离均匀的等离子体波腔：载流子密度和等离子体速度向漏极方向减小，而电子漂移速度则增大。这种电流引起的空间非均匀性改变了等离子体波的传播时间和放大，并且随着接近声速区域而变得越来越重要。利用流体动力学描述结合统一电荷控制模型，我们确定了非均匀稳态，并分析了由此产生的等离子体波频率和不稳定性增长率。研究发现，振荡频率由整个通道中的波传播决定，而非局部漏极条件，从而导致明显的电流引起的频率降低，这是均匀通道近似无法捕捉的。不稳定性源于边界诱导的等离子体波增益与动量弛豫和电子粘性引起的分布式损耗之间的竞争。有限粘性理论在亚声速区域内与模拟数据表现出良好的定量一致性，并对无粘描述在声速点附近的奇异行为进行了正则化。在更高电流下，动力学对近声速结构和接触边界条件变得越来越敏感，表明不稳定性的最终抑制不能仅归因于体流体动力学。
英文摘要：
We report a theoretical and numerical study of plasma-wave instability in a current-driven InGaAs/GaAs gated electron channel. A finite drain current drives the channel away from a uniform plasma-wave cavity: the carrier density and plasma velocity decrease toward the drain, while the electron drift velocity increases. This current-induced spatial nonuniformity modifies both the propagation time and amplification of plasma waves and becomes increasingly important as the sonic regime is approached. Using a hydrodynamic description combined with the unified charge-control model, we determine the nonuniform steady state and analyze the resulting plasma-wave frequency and instability growth rate. The oscillation frequency is found to be governed by wave propagation through the entire channel rather than by the local drain conditions, leading to a pronounced current-induced frequency reduction that is not captured by a uniform-channel approximation. The instability results from the competition between boundary-induced plasma wave gain and distributed losses due to momentum relaxation and electron viscosity. The finite-viscosity theory shows good quantitative agreement with the simulation data over the subsonic regime and regularizes the singular behavior of the inviscid description near the sonic point. At higher currents, the dynamics become increasingly sensitive to the near-sonic structure and contact boundary conditions, indicating that the eventual suppression of the instability cannot be attributed to bulk hydrodynamics alone.
